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How to build Mini Metronome
October 13, 2010 - category: MetronomeLinear scale Small size
40 to 208 beats per minute
Circuit diagram
Parts:
- P1 100K Linear Potentiometer
- R1 10K 1/2W Trimmer Cermet
- R2 10K 1/4W Resistor
- R3 330K 1/4W Resistor
- R4 50K 1/2W Trimmer Cermet
- R5 100K 1/4W Resistor
- R6,R7 1K 1/4W Resistor
- C1 1µF 63V Polyester Capacitor
- C2 10nF 63V Polyester Capacitor
- C3 47µF 25V Electrolytic Capacitor
- IC1 NE555 General purpose timer IC
- Q1,Q2 BC560 45V 100mA Low noise High gain PNP Transistors
- Q3 ZTX753 100V 2A PNP Transistor
- SW1 SPST Switch (Ganged with P1)
- SPK 8 Ohm 40mm. Loudspeaker
- B1 12V Battery (MN21, GP23A or VR22 type)
Notes:
- Q1 & Q2 provide linear frequency operation of IC1 following P1 resistance variation.
- Q3 was added in order to obtain a louder click, similar to clockwork metronomes.
- 12V micro battery was used to obtain more output power and more compactness.
- Rotate P1 fully towards R2, then set R1 to obtain 40 beats per minute (compare with another metronome).
- Rotate P1 fully towards R3, then set R4 to obtain 208 beats per minute.
- Finally mark the entire scale with the usual metronome steps as following:
40 - 42 - 44 - 46 - 48 - 50 - 52 - 54 - 58 - 60 - 63 - 66 - 69 - 72 - 76 - 80 - 84 - 88 - 92 - 96 - 100 - 104 - 108 - 112 - 116 - 120 - 126 - 132 - 138 - 144 - 152 - 160 - 168 - 176 - 184 - 192 - 200 - 208.
author: RED Free Circuit Designs
circuit from http://www.redcircuits.com/
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